Ok, I have a 1987 F150 that has a 1994 351W running off of a 1989 ECM with the original 1987 harness. I have no Cat, the A.I.R. system at the back of the heads has been long taken off and plugged, and the air pump has been replaced with a bypass pulley.

I want to clean up my engine bay, so I've already taken out my CC can and vacuum lines and plugged them on the tree, and now I want to see if I can take off the rest of the TAB, TAD, (and there's one more, I can't remember the name) vacuum lines and possibly the solenoids all together.....as well as the vacuum line to the EGR valve

Is this possible to do without making it run rough/bad, and/or make it possibly run better?

 

Since you already took the air pump off, the TAB and TAD solenoids controlling the Bypass and Diverter valves don't have any air to Bypass or Divert. And since you already took the cat off, and also removed the air pipes to the back of the cylinder heads, there is no place for air to be pumped to, anyway.

So I think you could take those two off! That's assuming an 1989 ECM doesn't have the capability to sense that the line drivers in the ECM are no longer hooked up to a load, and sets a trouble code, lighting the CEL.

I wonder how your oxygen sensor is liking the changes you made.

 

well, either way, the only thing pre-O2 sensor is the EGR valve (so might have to leave that one on as well?..... everything else is post added in, so I would think it would be fine....

 

Removing the TAB nad TAD solenoids will set codes, you can get around it by removing the vacuum lines and simply leaving them electrically connected.

Same goes for the EGR but in that case if the computer doesn't see the valve move when commanded to it will also set a code, so you need to retain the vacuum line between the EVR solenoid(near the coil) and the EVP sensor on top of the EGR valve.

 

you can wire in 82 ohm 3 watt wirewound resistors instead of that tab and tad solinoids.